Blading with branches on the shroud of an axial-flow turbomachine compressor

ABSTRACT

The invention relates to an axial-flow turbomachine blading comprising a semi-circular row of blades extending radially. Each blade comprises a airfoil and lateral branches or lateral legs. Each branch has an end joined to the airfoil and an end opposite the airfoil. The blading comprises a first shroud segment connected to at least two opposite ends of two adjacent branches of two adjacent blades and/or of the same blade so as to connect the airfoils to the shroud segment via the lateral branches of the airfoils. The blading also comprises a second shroud segment concentric with the first shroud segment. The segments are connected to one another via the airfoils and the branches. The blading forms a rigid casing and is provided by additive manufacturing with a titanium-based powder.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit, under 35 U.S.C. §119, of EP14177989.2, filed Jul. 22, 2014, the disclosure of which is incorporatedherein by reference in its entirety.

FIELD

The invention relates to a turbomachine blade. More precisely, theinvention relates to a turbomachine blade comprising branches. Theinvention also relates to a blading with a row of branched blades. Theinvention also relates to a turbomachine comprising a blade havingbranches and/or a blading with a row of branched blades.

BACKGROUND

An axial-flow turbomachine blade generally has a profiled airfoilextending in the flow of the turbomachine. To reduce the number ofblades in a row whilst maintaining performance, it is known to provide ablade with branches.

Document FR 2 914 943 A1 discloses a fan blade of an axial-flowturbomachine. The blade comprises a first portion extending from a fanmeans, and a plurality of other portions extending the first portionradially outwardly. All of these portions are connected by a platformdisposed at the outer end of the first portion. However, this bladedesign has reduced rigidity. The presence of the platform in the middleof the fluid stream can disturb the flow. During operation, the branchesare subjected to vibrations and forces that can damage the blade. Theblade has a significant mass. The presence of the branches stresses theplatform; the mechanical strength of the platform means it has to bemade thicker, which disturbs the flow.

SUMMARY

One object of the invention is to overcome at least one of the problemsposed by the prior art. More precisely, one object of the invention isto increase the rigidity of a turbomachine blade with branches. Afurther object of the invention is to make rigid a turbomachine bladingwith branched blades. Another object of the invention is to protect theturbomachine in the event of ingestion.

The invention relates to a blading of an axial-flow turbomachine,comprising a circular or semi-circular row of blades extending radially,each blade comprising a airfoil and lateral branches, each branch havingan end joined to the airfoil and an end radially opposite the airfoil,noteworthy in that it also comprises a shroud or a shroud segmentconnected to at least two opposite ends of two adjacent branches of twoadjacent blades and/or of the same blade so as to connect the airfoilsto the shroud or to the shroud segment via the lateral branches of theairfoils.

In accordance with various advantageous embodiments of the invention atleast one or each branch is generally inclined in relation to the radialdirection and/or in relation to any perpendicular to the surface of theshroud or the shroud segment.

In accordance with various advantageous embodiments of the invention atleast one or each branch comprises a radial portion extendingperpendicularly from the shroud or the shroud segment.

In accordance with various advantageous embodiments of the invention theblade row comprises at least two blades with branches joined to theshroud and a blade of which the airfoil has an end joined to the shroud,the blades can be connected to one another on the radial side oppositethe shroud.

In accordance with various advantageous embodiments of the invention thebranches and the shroud form a conduit, e.g., a continuous conduit,passing through the airfoil.

In accordance with various advantageous embodiments of the invention atleast one or each branch extends over the axial majority of the shroud.

In accordance with various advantageous embodiments of the invention atleast one or each branch comprises a fixing portion passing through anopening formed in the shroud, the fixing portion comprising a fixingorifice formed on the branch or a surface with bumps sealed to theshroud.

In accordance with various advantageous embodiments of the invention thebranches of at least one blade or of each blade are integral with theshroud and the associated airfoil; the branches, the airfoils and theshroud being made by powder-based, e.g., metal powder-based, additivemanufacturing.

In accordance with various advantageous embodiments of the invention atleast one or each branch comprises a leading edge and a trailing edge,at least one, e.g., each leading edge and each trailing edge, e.g.,extending perpendicularly from the shroud.

In accordance with various advantageous embodiments of the invention thebranches of at least two adjacent blades are joined, the adjacentbranches of each pair of adjacent blades can be joined.

In accordance with various advantageous embodiments of the invention theblades form a plurality of sets of blades, the branches of a set ofblades being joined to adjacent branches of adjacent blades within thesame set, the adjacent branches of at least two adjacent sets of bladesbeing arranged at a distance in the circumferential direction of theshroud or of the shroud segment.

In accordance with various advantageous embodiments of the invention thejoined branches of two adjacent blades delimit therebetween a channelalong the entire length of the airfoil, the channel can be continuousand radially distant from the shroud.

In accordance with various advantageous embodiments of the invention theshroud is a first shroud, or the segment is a first shroud segment, theblading also comprising a second shroud or a second shroud segmentconcentric with the first shroud or with the first shroud segmentrespectively, the blades extending radially between the shrouds or theshroud segments.

In accordance with various advantageous embodiments of the invention atleast one blade or each blade comprises branches connected to the firstshroud and other branches connected to the second shroud or to the firstshroud segment and to the second shroud segment respectively.

In accordance with various advantageous embodiments of the invention ablading can comprise at least three blades, e.g., at least four blades.

In accordance with various advantageous embodiments of the invention ablading extends at least over a sixth and e.g., over at least a quarterof a circle, e.g., over a semi-circle.

In accordance with various advantageous embodiments of the invention theends of the branches are opposite ends over the height of the airfoil.

In accordance with various advantageous embodiments of the invention thebranches comprise joining edges at least partially coincident so as tojoin the branches on one another along the airfoil.

In accordance with various advantageous embodiments of the invention thejoining edges of the branches are joined over the majority, e.g., overall of their lengths L and/or the length of the chord of the airfoil.

In accordance with various advantageous embodiments of the invention theairfoils and/or the branches comprise leading edges and trailing edges,the leading edge of the airfoil being extended radially by the leadingedges of the branches, and/or the trailing edge of the airfoil beingextended radially by the trailing edges of the branches.

In accordance with various advantageous embodiments of the invention theleading edges and the trailing edges of the branches are tangential tothe leading edge and to the trailing edge of the airfoil, respectively.

In accordance with various advantageous embodiments of the invention themean thickness of the aerodynamic profiles of the branches is less thanthe mean thickness of the profiles of the airfoil.

In accordance with various advantageous embodiments of the inventioneach airfoil comprises an intrados surface and an extrados surface, theintrados surface and/or the extrados surface of the airfoil beingtangential to the intrados surface of a branch and/or to the extradossurface of a branch.

In accordance with various advantageous embodiments of the invention thebranches have the same radial heights and/or the same axial lengths.

In accordance with various advantageous embodiments of the invention atleast one or each branch has a height H2 greater than 5%, e.g., greaterthan 10%, e.g., greater than 20% of the height H1 of the airfoil.

In accordance with various advantageous embodiments of the invention theblade is a compressor blade, e.g., a low-pressure compressor blade, or aturbine blade, or a fan blade.

In accordance with various advantageous embodiments of the invention thelength of the chord of the airfoil is greater than or equal to the chordof each branch, or less than the chord of each branch.

In accordance with various advantageous embodiments of the invention thebranches, from the airfoil, converge towards one another over theirheight H2 and their length L.

In accordance with various advantageous embodiments of the invention theairfoil divides over the thickness thereof into a plurality of branches.

In accordance with various advantageous embodiments of the invention thebranches delimit the airfoil radially.

In accordance with various advantageous embodiments of the invention,the blading is a stator blading or a rotor blading.

The invention also relates to a blading that has a row of blades eachcomprising a airfoil extended radially by branches, the branches ofadjacent blades being joined so as to connect the blades via thebranches thereof, the branches of the blades can be disposed at the sameend of the airfoil or at each radial end of the airfoil so as to connectthe blades to one another at each airfoil end.

The invention also relates to a turbomachine comprising at least oneblading, noteworthy in that the at least one or each blading is formedin accordance with the invention, in various instances the turbomachinecan comprise a compressor that has rows of bladings, at least one oreach compressor blading being formed in accordance with the invention.

Each advantageous embodiment of the invention can apply to the otherobjects of the invention. Each object of the invention can be combinedwith the other objects of the invention.

The invention makes it possible to make the blade rigid. In fact, thebranch airfoils form an angle at the end of the joining airfoil wherethe branch airfoils are joined. The edge of the joining airfoil is maderigid, the mechanical strength thereof no longer being dependent solelyon the central part of the joining airfoil. As a result, the centralpart can be made thinner and further optimized. The aerodynamic gain andthe strengthening make it possible to reduce the number of blades in ablade stage.

The invention makes it possible to strengthen the blading by formingjoints between the adjacent lateral branches. The shroud or the shroudsegment forms a bridge connecting the ends of the branches within thesame blade, or connecting the ends of the branches of one blade toanother adjacent blade. The branches are thus protected againstvibrations, which could damage the branches.

The presence of branches between a airfoil and a shroud multiplies theanchoring points, the transmission zones and the distribution of forces.The joining of two adjacent blade branches also makes it possible todistribute forces in different blades. In addition, the formation ofspacings in a row of connected branches makes it possible to optimizethe flexibility, the rigidity and the transmission of forces in ablading.

The invention makes it possible to increase the number of airfoils thatcould intercept a body in the event of ingestion. The body can be sloweddown and, in various instances, can be trapped or further divided thanksto the added leading edges. The ingested bodies thus tend to be reducedupstream, which makes it possible to protect the elements downstream.The positioning of branches at the end of the airfoil makes it possibleto act effectively against the fragments in the vicinity of the walls ofthe fluid streams, which constitute locations where the fragments arefrequently found due to flow dynamics and/or inclinations of the fluidstreams.

The configuration in which the branches overlap axially makes itpossible to form reinforcements making the airfoil rigid. The airfoilcan thus be made thinner and lighter because it is less exposed totorsion. The profiles of the airfoil can be better adapted to theaerodynamic needs. This configuration strengthens the connectionsbetween the branches, which makes the branches more resistant toingestions.

DRAWINGS

FIG. 1 shows an axial-flow turbomachine according to various embodimentsof the invention.

FIG. 2 shows a diagram of a turbomachine compressor according to variousembodiments of the invention.

FIG. 3 illustrates a blading in accordance with various embodiments ofthe invention.

FIG. 4 illustrates a blading in accordance with various otherembodiments of the invention.

FIG. 5 illustrates a blading in accordance with yet other embodiments ofthe invention.

FIG. 6 illustrates a blading in accordance with still other embodimentsof the invention.

FIG. 7 illustrates a blading in accordance with still yet otherembodiments of the invention.

FIG. 8 illustrates a blade in accordance with various embodiments of theinvention.

FIG. 9 illustrates a blade in accordance with yet other embodiments ofthe invention.

FIG. 10 illustrates a blade in accordance with still yet otherembodiments of the invention.

DETAILED DESCRIPTION

In the description below the terms internal or inner and external orouter relate to a positioning in relation to the axis of rotation of anaxial-flow turbomachine.

FIG. 1 shows an axial-flow turbomachine in a simplified manner. In thisspecific case the axial-flow turbomachine is a bypass turbojet. Theturbojet 2 comprises a first compression level, referred to as alow-pressure compressor 4, a second compression level, referred to as ahigh-pressure compressor 6, a combustion chamber 8, and one or moreturbine levels 10. During operation the mechanical power of the turbine10 transmitted via the central shaft to the rotor 12 sets in movementthe two compressors 4 and 6. The different turbine stages can each beconnected to compressor stages via concentric shafts. The shafts have aplurality of rows of rotor blades associated with rows of stator blades.The rotation of the rotor about the axis of rotation 14 thereof thusmakes it possible to generate a flow of air and to progressivelycompress the flow of air as far as the inlet of the combustion chamber8.

An inlet ventilator referred to commonly as a fan or blower 16 iscoupled to the rotor 12 and generates a flow of air that is divided intoa primary flow 18 passing through the different above-mentioned levelsof the turbomachine and a secondary flow 20 passing through an annularconduit (shown in part) along the length of the machine so as to thenre-join the primary flow at the outlet of the turbine. The secondaryflow can be accelerated so as to generate a reaction. The primary flow18 and secondary flow 20 are annular flows and are channeled by thecasing of the turbomachine. For this purpose, the casing has cylindricalwalls or shrouds, which can be internal and external.

The turbomachine can comprise a compressor or a compressor portion inwhich the flow circulates radially. The turbomachine can also comprise asimilar turbine. The blades, in particular the leading edges thereofand/or the trailing edges thereof, can extend radially or axially.

FIG. 2 is a sectional view of an axial-flow turbomachine compressor 2such as that in FIG. 1. The compressor can be a low-pressure compressor4. Here, part of the fan 16 and the separation beak 22 of the primaryflow 18 and the secondary flow 20 can be seen. The rotor 12 comprises anumber of rows of rotor blades 24, in the present case three.

The low-pressure compressor 4 can comprise a plurality of rectifiers, inthe present case four, which each contain a row of stator blades 26. Therectifiers are associated with the fan 16 or with a row of rotor bladesin order to rectify the flow of air so as to convert the speed of theflow into pressure.

The stator blades 26 extend essentially over the height thereof throughthe flow 18, e.g., radially, from an outer casing 28 and can be fixedthere with the aid of a pin, e.g., formed on a fixing platform.

The blades (24, 26) can be fixed individually to the stator or to therotor 12, or can be grouped into bladings comprising a plurality ofblades forming a row over the circumference. The blades (24, 26) can begrouped into bladed casings, with a plurality of blades and a shroud, orwith two concentric shrouds (30, 32) between which the blades (24, 26)extend radially.

A blading can be monoblock, e.g., it can be formed in one piece,possibly thanks to an additive manufacturing process. It can also beformed by soldering branches and airfoils to one another.

The rotor blades 24 and/or the stator blades 26 of the compressor can bebranched. The branch designs can vary from one blade row to the otherand can be branched at the blade foot and/or blade head. The joints 27between the branches and the blade airfoils are visible.

FIG. 3 shows a turbomachine blading 34 in accordance with variousembodiments of the invention. The blading 34 shown is a stator blading,but could also be a rotor blading.

A blading 34 can be understood to be a surface, e.g., a rigid surface,making it possible to guide a flow of fluid. It can be understood to bea set of blades 26. The blading can be and/or can comprise a row ofblades, with a plurality of blades 26, forming a portion of an annularrow. The blades 26 are disposed on a wall, such as a shroud or a shroudportion, e.g., an inner shroud portion 32. The wall, or shroud portioncan have the shape of a circle or arc of a circle.

Each blade 26 can protrude, e.g., extend radially, from the shroud 32.Each blade 26 comprises a airfoil 36 and branches 38. The airfoil 36 canbe a joining airfoil 36 combining the branches 38, the branches can bebranch airfoils 38. The branches 38 of the same blade are spaced fromone another in the circumferential direction.

Each airfoil 36 and/or each branch 38 can have a general leaf shape,which can generally extend in a primary plane, the leaf can besubstantially curved and/or having a variable thickness. An airfoil hasa leading edge 40 and a trailing edge 42, which delimit an intradossurface and an extrados surface.

The branches 38 can be lateral branches 38 in the sense that they arelaterally spaced from the airfoil 36 in the direction of thicknessthereof and/or perpendicularly to the court of the airfoil 36. Eachbranch 38 has two opposite ends in the direction of height, e.g., theradial height, of the airfoil. One of the ends is joined to the airfoil36 and the other is joined to the shroud 32, which forms a support. Theshroud 32 and the blades can be formed integrally, or the shroud cancomprise openings 44 in which the ends of the branches are fixed and/orsealed.

The shroud 32 can be a portion of an outer casing, or a rotor wall, suchas a rotor drum wall. The shroud can form a circle or an angular portionof a circle, such as an arched material strip.

The height of a branch 38, of an airfoil 36, or of the blade 26 can beperpendicular to the leading edge and/or the trailing edge of theairfoil, and/or can be oriented perpendicularly to the fluid. Theairfoil and the branches are intended to extend in the flow of theturbomachine.

The branches 38 of adjacent blades 26 are distanced from one another andallow a passage between the blades along the extrados surface of theshroud 32. In combination with the shroud, the branches of at least oneor each blade form a conduit 48, which passes through the blade 26. Thisconduit 48 is configured to support a flow of the turbomachine. Theupper ends of the airfoils are free and form edges.

FIG. 4 shows a blading 134 in accordance with various other embodimentsof the invention. This FIG. 4 adopts the numbering of the previousfigures for identical or similar elements, however the numbering isincremented by 100. The figure shows a row of blades 126, which invarious instances can include a shroud. Each blade 126 is shown in theform of a curve, which can correspond to a leading edge and/or to atrailing edge and/or to a stacking curve of aerodynamic profiles of anairfoil or branch.

The row comprises a plurality of blades 126, each with branches 138 atthe same end or on a same side of the airfoil 136. The branches 138extend over the circumference in the direction of the adjacent blade126, and in particular of the branches 138 of the adjacent blades. Theadjacent branches 138 of two adjacent blades 126 are joined, for exampleat a radial end of the blade, such as the end opposite the end receivingthe airfoil. Thus, the blades 126 form a chain of blades, withcontinuation of circumferential material, which are connected to oneanother with the aid of their branches 138.

The term joined can mean that the branches 138 or the branch airfoils138 comprise joining edges or coincident edges. At the joining point ofthe branches, the total thickness can be less than the addition of thethicknesses of each branch.

At least two adjacent branches or each pair of adjacent branches 138 ofadjacent blades 126 can form therebetween a channel 150. A channel 150can be understood to mean an elongate depression, such as a passagedelimited laterally between two opposite branch walls.

FIG. 5 shows a blading 234 in accordance with yet other embodiments ofthe invention. This FIG. 5 adopts the numbering of the previous figuresfor identical or similar elements, however the numbering is incrementedby 200.

The blading 234 comprises a row of blades 226 with a plurality of bladesforming an angular portion of an annular row. The row can form a circle.The blades 226 are disposed on a wall, such as a shroud (230, 232) or ashroud portion. The wall or shroud portion can have the shape of acircle or arc of a circle.

The blading can be a bladed casing. It can comprise at least threeblades 226 each with a airfoil and branches extending the airfoil in thedirection of the radial height of the airfoil. The blades, including thebranches thereof, can be distanced from one another.

The blading 234 comprises two shroud segments, such as an inner shroudsegment 232 and an outer shroud segment 230, which can be understood tobe angular sectors of tubes. The segments are concentric and define afluid stream of which the middle in the radial height direction islocated in line with the airfoil, e.g., at mid-height.

At least one or each blade 226 can comprise two sets of branches 238,which are each joined to one end of the airfoil 236 and to a shroudsegment (230, 232). The shroud segments are thus connected to oneanother via, in this order, first sets of branches 238, airfoils 236,and second sets of branches 238. Each branch is joined to the bladeand/or to a shroud over the majority, e.g., over the entire lengththereof.

The sets of branches 238 of at least one blade or each blade can havedifferent numbers of branches. The sets having most branches 238 can bearranged on the same side of the airfoil 236. The arrangements ofbranches can vary from one set to another adjacent set.

For example, one set can comprise at least three branches, of which twobranches 238 are side branches over the circumference, between which atleast one central branch 238 is disposed. These branches 238 can all bejoined by each having a joining edge; the edges being coincident. Atleast one or each blade 226 can have branches 238 that are joined to theairfoil 236 at different heights. A branch 238 can extend from anotherbranch 238 remaining at a distance from another branch and/or from theairfoil 236. A branch 238 of this type can form a strut that makes theblading 234 rigid. A branch 238 can extend laterally from one side ofthe airfoil 236, then from the other, or can extend only from one sideof the airfoil 236.

FIG. 6 shows a blading 334 in accordance with still other embodiments ofthe invention. This FIG. 6 adopts the numbering of the previous figuresfor identical or similar elements, however the numbering is incrementedby 300. The blading shown is a stator blading, but alternatively couldbe associated with the rotor.

The blading 334 has a plurality of sets of blades. Each set can form anangular portion of an annular row of blades. Each set of blades has aplurality of blades 326, each with a airfoil 336 and branches 338extending the airfoil 336 in the direction of height thereof, e.g., inthe direction of radial height thereof. Each blade 326 can have two setsof branches. Adjacent branches 338 of a set of blades 326 can be joinedon a radial side, the branches 338 remaining at a distance on the otherside. The sets of blades can be distanced from one another. Inparticular, the branches of a set of blades can be distanced, over thecircumference, from each branch 338 of an adjacent set of blades.

FIG. 7 shows a blading 434 in accordance with still yet otherembodiments of the invention. This FIG. 7 adopts the numbering of theprevious figures for identical or similar elements, however thenumbering is incremented by 400. Specific numbers are used for theelements specific to this embodiment.

The blading 434 comprises a row of blades 426 forming at least oneportion of an annular turbomachine row. The blades 426 are disposed on awall, such as a shroud or a shroud portion (430, 432). The wall orshroud portion can have the shape of a circle or an arc of a circle.

The row can have a mixed arrangement of blades 426. Some blades 426 canbe free from branches at least at one end or at each end. The number ofbranches 438 on the same radial side of the blading can vary between theblades 426. Some, e.g., all the adjacent branches 438 of differentblades 426 can be joined. On one radial side of the blading, thebranches can form a row and/or maybe joined to one another so as to forma chain of branches 438, which can also be joined to a shroud 430 inaddition to associated airfoils 436. This double joining of the branchesmakes the shroud rigid and the arts makes the blading rigid with respectto torsional forces.

FIG. 8 shows a blade 526 in accordance with various embodiments of theinvention. This FIG. 8 adopts the numbering of the previous figures foridentical or similar elements, however the numbering is incremented by500. Specific numbers are used for elements specific to this embodiment.The blade 526 can be a stator blade 526 as shown in FIG. 2.

The blade 526 comprises a airfoil 536 and at least two branches 538,e.g., three or more branches 538. The airfoil 536 can be a joiningairfoil 536 or a main airfoil 536 in the sense that the height and/orthickness thereof is greater than that of each branch 538. The joiningairfoil 536 forms a joining portion 552, and the branches 538 form abranch portion 554, the portions being superimposed in the heightdirection.

The branches 538 can be branch airfoils 538 that are joined by thejoining airfoil 536. For this purpose they can comprise joining edgesthat are at least partially, e.g., completely coincident along the chordof the joining airfoil. The joining edges 556 can form ends ordelimitations of the branch airfoils 538. The joining airfoil 536 andthe branch airfoils 538 are intended each to be disposed in the flow ofthe turbomachine.

The joining airfoil 536 is disposed in the extension of the branchairfoils 538 at the joining point therebetween. The joining airfoil 536can form the joining point between the branch airfoils 538. These canform divisions of the joining airfoil. They can form legs 538 separatingfrom the joining airfoil at a branching point. The joining airfoil 536can divide or separate into branch airfoils. The branches can beanchored to one another and/or on one another.

The joining airfoil 536 and/or each branch airfoil 538 can comprise aleading edge 540 and a trailing edge 542. The joining airfoil and/oreach branch airfoil can comprise an intrados surface and an extradossurface extending from the leading edge 540 to the correspondingtrailing edge 542. The intrados surface and the extrados surface of thejoining airfoil are tangential, e.g., along the entire length of thechord of the airfoil, to the adjacent surfaces of the branch airfoils538.

The joining airfoil 536 and/or each branch airfoil 538 can compriseaerodynamic profiles 558, which can be cambered and which are stacked inthe height direction, e.g., in the radial height direction. The centresof gravity of the aerodynamic profiles 558 of the joining airfoil 536and/or of each branch airfoil 538 can describe a stacking curve 560. Thestacking curves 560 of the branch airfoils 538 can be in the radialand/or axial and/or circumferential extension of the stacking curve 560of the joining airfoil 536, in various instances, becoming progressivelyoffset in relation thereto. The branch airfoils can define a channel 562therebetween, in various instances at a distance from the joiningairfoil 536. The height H1 of the joining airfoil 536 can be greaterthan or equal to the height H2 of each branch airfoil 538.

The leading edges 540 and/or the trailing edges 542 and/or the stackingcurves 560 of each branch airfoil 538 can have a variation, e.g., anincrease, and/or an inversion of curvature in relation to, respectively,the leading edge 540 and/or the trailing edge 542 and/or the stackingcurve 560 of the joining airfoil 536.

The maximum thickness of the aerodynamic profiles 558 of the joiningairfoil 536 can be greater than the maximum thickness of the aerodynamicprofiles 558 of each branch airfoil 538. The surface of each aerodynamicprofile 558 of the joining airfoil can be greater than or equal to thesurface of each aerodynamic profile of at least one or each branch. Theaddition of the surfaces of the aerodynamic profiles of the branches ata given height can be greater than or equal to the surface of eachaerodynamic profile of the airfoil.

The blade 526 has at least two branch airfoils 538, e.g., three or four,or even more at one end. The blade 526 can comprise a support 564 joinedto the branch airfoils. The support 564 can be a fixing platform 564,for example equipped with a fixing pin 566. The branch airfoils 538, thejoining airfoil 536, and in various instances the support 562 can beintegral. They can be provided by additive manufacturing with a titaniumpowder.

At least one or each branch airfoil 538 can comprise parts, over theheight of the blade, that are inclined in relation to one another. Theseparts can be curves and can have variations or inversions of curvature.Along the height, the mean axis of the stacking curve 560 of at leastone or each branch airfoil 538 is inclined in relation to that of thejoining airfoil 536. These geometries can be observed at the leadingedge 540 and/or the trailing edge 542 and/or the stacking curve 560 ofthe profiles 558.

The distance E between the branch airfoils 538, measured opposite thejoining airfoil 536 at the leading edges 540 thereof or at the trailingedges 542 thereof or at the maximum passage width, is greater than themajority of the mean or maximum thickness of the joining airfoil 536.The distance E can be less than the length L of the branch airfoils 538and/or less than the height H2 of the branch airfoils. For at least oneor each branch airfoil 538, the length L can be greater than or equal tothe height H2.

FIG. 9 shows a blade 626 in accordance with yet other embodiments of theinvention. This FIG. 9 adopts the numbering of the previous figures foridentical or similar elements, however the numbering is incremented by600. Specific numbers are used for the elements specific to thisembodiment.

The blade 626 comprises two branched portions 654 joined by a joiningportion 652. The joining airfoil 636 of the blade 626 comprise two ends668 that are opposite over the height of the joining airfoil, forexample radial ends, such as a head and a foot. The joining airfoil 636can comprise branch airfoils 638 at each of the radial ends thereof, thebranch airfoils forming a first set and a second set of branch airfoils638, each set being joined to one of the ends 668 of the joining airfoil636. The height H2 of the branch airfoils can vary from one set toanother and can remain less than the height H1 of the joining airfoil636.

The ends of branch airfoils can be free edges 670. They can form edgesin the form of cambered aerodynamic blade profiles. The ends can havefixing means, such as fixing pins. The ends at the same end of a bladecan each comprise a fixing orifice 672, the orifices 672 can be alignedalong the row formed by the associated branch airfoils.

FIG. 10 shows a blade 726 in accordance with still yet other embodimentsof the invention. This FIG. 10 adopts the numbering of the previousfigures for identical or similar elements, however the numbering isincremented by 700. Specific numbers are used for the elements specificto this embodiment.

The blade 726 comprises a joining airfoil 736 with two ends 768 that areopposite in the height direction H1, each end 768 comprising branches738 extending the airfoil in the height direction. Branches form a firstset of branches at one end 768 of the airfoil 736, and a second set ofbranches 738 at the other end 768. The opposite ends 768 comprise adifferent number of branches 738.

The sets of branches can be superimposed in the height direction of theblade 726 whilst being separated by the airfoil 736. One of the sets cancover the other set, the covering can be over the mean chord of theairfoil and/or over the thickness of the airfoil.

One set of branches can be connected to a support 764, such as a fixingplatform 764. The set of branches on the side opposite the support 764can have free edges 770, and in various instances a fixing means 774,such as bosses 774 or bumps 774. These means can be used to seal thebranches to a wall, to a support, or to a shroud.

The various embodiments of the blades described and illustrated withregard to FIGS. 3 and 7 can be formed in accordance with the variousembodiments described and illustrated with regard to FIGS. 8, 9 and 10.A blading can comprise branches at each end over the height of theairfoils. The number of branches can be different at each of these ends.The various embodiments of the blades described and illustrated withregard to FIGS. 9 and 10 can adopt the configurations of the bladedescribed and illustrated with regard to FIG. 8; in particular withregard to the arrangement of the leading edges, the trailing edges, thejoining edges, the stacking curves, and the arrangement of the branchairfoils in relation to the joining airfoil.

What is claimed is:
 1. A blading of an axial-flow turbomachine, saidblade comprising: a semi-circular row of blades extending radially, eachblade comprising: an airfoil and lateral branches, each branchcomprising: a first end joined to the airfoil; and a second end radiallyopposite the airfoil; and a shroud connected to at least two second endsof two adjacent branches of two blades so as to connect the airfoils tothe shroud via the lateral branches of the airfoils.
 2. The blading inaccordance with claim 1, wherein the branches separate the correspondingairfoil from the platform.
 3. The blading in accordance with claim 1,wherein each blade comprises a branch more inclined than thecorresponding airfoil with respect to the radial direction.
 4. Theblading in accordance with claim 1, wherein the blade row comprises atleast three adjacent blades whose second ends are connected to theshroud.
 5. The blading in accordance with claim 1, wherein the blade rowcomprises at least two blades with branches joined to the shroud and ablade of which the airfoil has an end joined to the shroud, the bladesbeing also connected to one another on the radial side opposite theshroud.
 6. The blading in accordance with claim 1, wherein each branchextends over the axial majority of the shroud.
 7. The blading inaccordance with claim 1, wherein the shroud comprises at least anopening, at least one branch comprises a fixing portion passing throughthe opening, the fixing portion comprising one of a fixing orificeformed on the corresponding branch or a surface with bumps.
 8. Theblading in accordance with claim 1, wherein the branches of at least oneblade are integral with the shroud and with the associated airfoil. 9.The blading in accordance with claim 1, wherein the shroud is a rotorannular wall, the blade being placed radially outside from the rotorannular wall.
 10. The blading in accordance with claim 1, wherein theblades form a plurality of sets of blades, the branches of a set ofblades being joined to adjacent branches of adjacent blades within thesame set, the adjacent branches of at least two adjacent sets of bladesbeing remote in the circumferential direction of the shroud.
 11. Theblading in accordance with claim 1, wherein the joined branches of twoadjacent blades delimit therebetween a channel along the entire lengthof the airfoil.
 12. The blading in accordance with claim 1, wherein theshroud is a first shroud, the blading also comprises a second shroudconcentric with the first shroud, the blades extending radially betweenthe shrouds and linking the shrouds.
 13. The blading in accordance withclaim 12, wherein at least one blade comprises branches connected to thefirst shroud and other branches connected to the second shroud.
 14. Theblading in accordance with claim 1, wherein the shroud is a shroudsegment.
 15. An axial flow turbomachine compressor, said compressorcomprising a blading, the blading comprising: an annular row of bladesextending radially, at least one blade comprising an airfoil and lateralbranches, each branch comprising: a first radial end joined to theairfoil; and a second radial end radially opposite the airfoil; and atleast a platform connected to at least two second ends of two adjacentbranches of the blade so as to connect its airfoils to the platform viathe lateral branches of the airfoils.
 16. The axial flow turbomachinecompressor of claim 15, wherein it comprises an outer annular casing,the platform being fixed to the casing, the platform being radiallyplaced between the lateral branch and the casing.
 17. The axial flowturbomachine compressor of claim 15, wherein the branches and theplatform form a passageway passing through the airfoil, between theairfoil and the branches.
 18. The axial flow turbomachine compressor ofclaim 15, wherein the casing comprises a circular array of fixationholes, the platforms comprising fixation axes fixed through the holes ofthe circular array of fixation holes.
 19. An axial flow turbomachine,said turbomachine comprising: an annular duct guiding an annular flow;and a blading, the blading comprising: a circular row of blades placedradially accord the annular flow, each blade comprising: an airfoil andlateral branches, each branch comprising: a first end joined to theairfoil; and a second end radially opposite the airfoil; and a shroudwhich delimits the annular flow, and which is linked to at least twosecond ends of two adjacent branches so as to connect the correspondingairfoil to the shroud via the lateral branches of the airfoils.
 20. Theaxial flow turbomachine of claim 19, wherein the second ends of theadjacent branches are remote from each other and are joined to adjacentairfoils.